With rapid development of a fiber to home (Fiber To Home, called FTTH for short below) technology which has a huge market scale, terminal users and optical link branches which are related to an access network are distributed complicatedly, the whole network adopts full fiber cabling, electrical signals cannot be utilized for monitoring, operation and maintenance, and therefore, an optical link detection system is required to perform the monitoring of the network maintenance, thereby ensuring network quality. In conventional monitoring systems, an optical time domain reflectometer (Optical Time Domain Reflectometer, called OTDR for short below) is mainly adopted to detect link performance, but the cost thereof is high, a 1*N optical switch is therefore adopted to reduce the use cost through N access terminals.
To guarantee stability of long-time working of the optical switch, a feedback mechanism is generally added into an optical switch system to ensure that the selection of the optical switch is consistent with parameters of factory setting, thereby guaranteeing that the optical performance of the optical switch does not change in any way after a certain period of working. In the prior art, the monitoring is carried out by adding a tap (Tap) and a photodetector (Photodetector, called PD for short below) at an output end. FIG. 1 shows a schematic structural diagram of a mechanical optical switch in the prior art, in which the Tap and the PD are set on both an input fiber and an output fiber, so as to detect whether optical power of a whole optical path satisfies a design requirement, and when an actual condition is inconsistent with the requirement, a feedback module instructs a control module to continuously adjust the optical path, so as to select an optimal optical path.
However, each branch of the optical switch system in the prior art needs a Tap and a PD, in which the cost is high, the design of the complete machine is complicated, the volume is large, and in particular, the foregoing problems are more serious for an optical switch with a large branching ratio.